Sunday, October 21, 2012

11 Basic Linux NMAP command Examples for System administrators

NMAP(Network Mapping) is one of the important network monitoring tool. Which checks for what ports are opened on a machine.
Some important to note about NMAP

NMAP abbreviation is network mapper

NMAP is used to scan ports on a machine, either local or remote machine (just you require IP/hostname to scan).

NMAPis can be installed on windows, Sun Solaris machines too.

NMAPcan be used to scan large networks, remember I am saying large networks.

NMAPcan be used to get operating system details such as open
ports, software used for a service and its version no, vendor of
network card and up time of that system too(Don’t worry we will see all
these things in this post.

Please do not try to use NMAP on machines which you don’t have permission.

Can be used by hackers to scan for systems for vulnerability.

Just a funny note : You can see this NMAP used by Trinity in
Matrix-II movie, when she tries to hack in to electric grid super
computer.

Note :MAN
pages of NMAP is one of the best man pages I have come across. It is
explained in such a way that even new user can understand what each
option do and one more thing is that, it even have examples in to on how
to use NMAP in different situations, when you have time read it. You
will get lots of information.
Let us start with some examples to better understand nmap command:

Check for particular port on local machine.

Use nmap to scan local machine for open ports.

Nmap to scan remote machines for open ports.

Nmap to scan entire network for open ports.

Scan only ports with -F option.

Scan a machine with -v option for verbose mode.

Scan a machine for TCP protocol open ports.

Scan a machine for UDP protocol open ports.

Scan a machine for services and their software versions.

Scan for open Protocols such as TCP, UDP, ICMP, IGMP etc on a machine.